A series of weather systems in the westerly flow moved across the country during this U.S. Drought Monitor (USDM) week. In the West, the systems moved across the Pacific Northwest, leaving the Southwest dry. Cyclonic storm systems energized over the central third of the country and moved east, trailing cold fronts in their wake. Several of these systems followed a track along the Gulf Coast and up the Atlantic Seaboard. The combination of moisture and cold Canadian air resulted in widespread snowfall. Snow has a lower moisture content than rain, so it takes more snow (on average, about ten times as much) to equal the same amount of precipitation (meltwater equivalent) that would fall as rain. These winter storm systems brought above-normal snowfall but below-normal rain to many drought areas, giving the impression of wet conditions when, in fact, total precipitation was below normal.
The Northeast and Mid-Atlantic: Above-normal precipitation fell over parts of the Northeast that were drought-free, but the rest of the Northeast and Mid-Atlantic had below-normal precipitation this USDM week. Long-term deficits continued to mount, with parts of Virginia falling 3 inches or more behind normal for the last 30 days and parts of Pennsylvania to Virginia more than 4 inches behind for the last 60 days. Streamflow levels were significantly below normal (in the bottom ten percentile) across much of the Gulf Coast states to southern Pennsylvania, with record low levels observed at many North Carolina and Virginia streams. Soil moisture models indicated continued drying potential, but the cold temperatures have minimized agricultural impacts. The abnormally dry (D0) area was expanded further into West Virginia and Pennsylvania and moderate drought with hydrological impacts (D1H) was extended into central Virginia. An area of D0 was introduced into northern New York, around the Adirondacks, where 90-day precipitation deficits approached 6 to 9 inches in places.
Southeast and Gulf Coast: Above-normal rainfall over southeast Texas to western Mississippi, and much of central Florida, benefited the drought areas, but the week was drier than normal across the rest of the region, especially northern Alabama to the Carolinas. Widespread 1-2 inch rains fell over Louisiana on the last day of the week, resulting in pullback of D1, severe drought (D2), and extreme drought (D3) where the heaviest rain fell and long-term deficits were smallest. In central Florida, D2 and D3 were pulled back where 1-2 inches of rain was measured. The AH impacts boundary was pulled back to the Georgia-South Carolina state line, leaving H impacts over the Carolinas. Long-term precipitation deficits resulted in low groundwater and stream levels and reduced inflows into reservoirs, with some streams in North Carolina reaching record low levels for the day, week, and month, but the cold weather minimized agricultural and other impacts there.